Supercooled water and the kinetic glass transition. II. Collective dynamics

In this article we study in detail the $Q$-vector dependence of the collective dynamics in simulated deeply supercooled extended simple-point-charge (SPC/E) water. The evolution of the system has been followed for 250 ns at low $T,$ allowing a clear identification of a two-step relaxation process. We present evidence in favor of the use of the mode-coupling theory for supercooled liquid as a framework for the description of the slow α-relaxation dynamics in SPC/E water, notwithstanding the fact that the cage formation in this system is controlled by the formation of an open network of hydrogen bonds as opposed to packing constraints, as in the case of simple liquids.